Field of the Invention
The present invention relates to a transparent display device and a method for fabricating the same.
Discussion of the Related Art
Recently, with the advancement of the information age, display devices for processing and displaying a large amount of information have been promptly developed. More particularly, various display devices have been introduced and spotlighted. Detailed examples of the display devices include liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, electroluminescence display (ELD) devices, and organic electroluminescent display (OLED) devices.
Recently, the display devices have excellent properties of a thin profile, light weight and low power consumption and thus their application fields have been increased continuously. In particular, in most of electron devices or mobile devices, the display device has been used as one of user interfaces.
Also, studies of a transparent display device through which a user may see objects or images disposed on a rear surface of the display device have been actively made. The transparent display device may have advantages of better use of space, interior and design, and may have various application fields. The transparent display device may solve spatial and temporal restrictions of the existing electron devices by realizing functions of information recognition, information processing and information display as a transparent electron device. For example, the transparent display device may be applied to a window of a building or a car, and thus may be used as a smart window that allows a background to be seen or displays an image.
The transparent display device may be realized as an organic light emitting display device that includes a transmissive area transmitting light and an emission area displaying an image. In this case, the transparent display device has an advantage of low power consumption. However, although the transparent display device has no problem in a contrast ratio under a dark environment, a problem occurs in that a contrast ratio is deteriorated under an environment that light exists. A contrast ratio of a dark environment may be defined as a dark room contrast ratio while a contrast ratio of an environment that light exists may be defined as a bright room contrast ratio. That is, since the transparent display device includes a transmissive area to allow a user to view an object or background disposed on a rear surface, a problem occurs in that a bright room contrast ratio is deteriorated. Therefore, if the transparent display device is realized as the organic light emitting display device, a light controlling device, which includes a light shielding mode shielding light and a transmissive mode transmitting light, is required to prevent a bright contrast ratio from being deteriorated.
The light controlling device may include a first substrate, a second substrate, a liquid crystal layer of a liquid state arranged between the first substrate and the second substrate, and partition walls for uniformly maintaining a gap of the liquid crystal layer. The light controlling device is bonded to a transparent display panel provided in a transparent display device by using a transparent adhesive film such as an optically clear adhesive (OCA) or a transparent adhesive such as an optically clear adhesive (OCA). To enhance transmittance in a transmissive mode of the transparent display device, it is preferable that the liquid crystal layer of the light controlling device is aligned in the transmissive area of the transparent display device. However, if the transparent display device and the light controlling device are not aligned normally during a bonding process of the transparent display device and the light controlling device, light transmittance in the transmissive mode may be deteriorated.